Although in theory alkylating agents such as TEM should be capable of inducing gene mutations in mammals, only a relatively small amount of data are available supporting this hypothesis. The objective of this study was to test the effectiveness of a chemical mutagen in inducing mutations at a number of different enzyme loci in the mouse. Strain DBA/2J male mice were exposed to triethylenemelimine (TEM) by i.p. injection. Control males were injected with the carrier (HBSS). Males were mated to C57BL/6J females. Kidneys and blood were obtained from all F1 offspring and said tissues were analyzed by starch gel electrophoresis for the occurrence of mutations at the various enzyme loci. A number of putative mutants have been identified in this experiment and progeny testing is underway to confirm these mutations.